16GB KIT (2 x 8GB) for HP-Compaq Workstation Series Z620 (ECC Registered) Z820 (ECC Registered). DIMM DDR3 ECC Registered PC3-12800 1600MHz Dual Rank RAM Memory. Genuine A-Tech Brand. 16GB KIT (2 x 8GB) DIMM DDR3 ECC Registered PC3-12800 1600MHz Dual Rank RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For HP-Compaq Workstation Series. (See Compatibility List Below)